Integration help

sexy girls SG

need help integrating this:

(1 - x tan x^2) dx

thanks a lot

wee_ws SG

Hi,

Consider the fact that -x tan x^2 = (-x sin x^2) / (cos x^2), which looks like the form f'(x) / f(x). Thanks.

Cheers,
Wen Shih

sexy girls SG

my answer is 1/2 [x + ln |cos x^2| ] + K

but its wrong

wee_ws SG

Hi,

The problem lies with "1/2 x" in your answer. How did it appear if we are integrating 1 with respect to x?

A good way to check your answer after integration, is to differentiate it to see if you are able to obtain the expression before it was integrated. If we were to differentiate

1/2 [x + ln |cos x^2| ] + K,

we will get 1/2 [1 - (2x sin x^2)/(cos x^2)] = 1/2 - x tan x^2,

which is not 1 - x tan x^2.

Thanks.

Cheers,
Wen Shih